[FFmpeg-devel] [PATCH] Wrong duration in TS container (Ticket #1836)

[Heesuk Jung]

>From ab16647265944baacaaf54a3f427ac366ee8874c Mon Sep 17 00:00:00 2001

From: Heesuk Jung <heesuk.jung at lge.com>

Date: Sun, 21 Oct 2012 13:21:23 +0900

Subject: [PATCH] Wrong duration in TS container (Ticket #1836)

 

Libavformat somtimes get wrong duration in some TS conatiner.

Please refer the problem description and file link in Ticket #1836.

(http://ffmpeg.org/trac/ffmpeg/ticket/1836)

 

I have just modified 2 point as below.

 

1. Duration determination considering time diff and file size / bit rate.

 

Duration is determined base on PTS time diff (end time - start ime) but

sometime is unreasonably so big.

I suggest that don't beleive duration based on PTS time diff

if time diff is bigger than hueristic value (file size / average bit rate *
2).

 

2. Change condition when estimate_timings_from_pts is called.

 

The estimate_timings_from_pts function is designed for MPEG-PS.

And so I changed condition from MPEG-TS to MPEG-PS

---

libavformat/utils.c |   32 +++++++++++++++++++++++++++++---

1 files changed, 29 insertions(+), 3 deletions(-)

mode change 100644 => 100755 libavformat/utils.c

 

diff --git a/libavformat/utils.c b/libavformat/utils.c

old mode 100644

new mode 100755

index 745dcaa..2a1fdbc

--- a/libavformat/utils.c

+++ b/libavformat/utils.c

@@ -2035,6 +2035,29 @@ static int has_duration(AVFormatContext *ic)

}

 /**

+ * examine if estimation from pts difference(end pts - start pts) is valid
or not.

+ * determine invalid duration if pts difference is un reasonably bigger
than file size/average bit rate.

+ * hueristically suggest  limit_filesize_multiple that means double file
size

+ * @return 1 if time_diff (end_time - start_time) is valid.

+ *         0 if time_diff (end_time - start_time) is not valid.

+ */

+static int valid_duration_from_pts(const int64_t start_time, const int64_t
end_time,

+                                    const int64_t filesize, int const
bit_rate)

+{

+    const const uint8_t limit_filesize_multiple = 2;

+         const int64_t time_diff = end_time - start_time;

+

+    if (bit_rate != 0) {

+        if (time_diff >
(filesize*8/bit_rate*limit_filesize_multiple*1000000)) {

+            return 0;

+        }

+        return 1;

+    } else {

+        return 0;

+    }

+}

+

+/**

  * Estimate the stream timings from the one of each components.

  *

  * Also computes the global bitrate if possible.

@@ -2077,8 +2100,11 @@ static void update_stream_timings(AVFormatContext
*ic)

     if (start_time != INT64_MAX) {

         ic->start_time = start_time;

-        if (end_time != INT64_MIN)

-            duration = FFMAX(duration, end_time - start_time);

+        if (end_time != INT64_MIN) {

+            if (valid_duration_from_pts(start_time, end_time,
avio_size(ic->pb), ic->bit_rate)) {

+                duration = FFMAX(duration, end_time - start_time);

+            }

+        }

     }

     if (duration != INT64_MIN && duration > 0 && ic->duration ==
AV_NOPTS_VALUE) {

         ic->duration = duration;

@@ -2233,7 +2259,7 @@ static void estimate_timings(AVFormatContext *ic,
int64_t old_offset)

     }

     if ((!strcmp(ic->iformat->name, "mpeg") ||

-         !strcmp(ic->iformat->name, "mpegts")) &&

+         !strcmp(ic->iformat->name, "mpegps")) &&

         file_size && ic->pb->seekable) {

         /* get accurate estimate from the PTSes */

         estimate_timings_from_pts(ic, old_offset);

-- 

1.7.0.4

 

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